1. Technical Field
The present invention relates in general to tracking by roller cone drill bits and, in particular, to an improved system, method, and apparatus for predicting and reducing tracking by roller cone bits by adjusting the spacing between the cutting elements.
2. Description of the Related Art
In the prior art, attempts to classify the adverse performance of “tracking” by roller cone bits have focused on either complex simulations of the entire bit or a single row of cutting elements on a single cone of a roller cone bit. For example, U.S. Pat. Nos. 6,516,293, 6,527,068, and 6,873,947, cover modeling and simulating roller cone performance, but require incrementally solving for the motions of individual cones. These complex simulations require substantial computation time and are therefore less useful to a designer during the initial design process.
A second class of simple simulations has traditionally focused on a single row of a single cone and has not acknowledged the effects that other rows of cutting elements on the same cone have on tracking. Additionally, some designs have varied the pitches of cutting elements in different formats, but typically incorporate arrangements of at least some of the cutting elements that may overload the most remote cutting element, which can result in breakage. Thus, solutions for improved tracking performance that overcome these limitations of the prior art would be desirable.